Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
| | Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990) |
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  (Pl. 24k): GS1161, Q8/f9687, Pakaurangi Point, Kaipara Harbour (probably from Pakaurangi Member, Pakaurangi Formation), Altonian (GNS) |
Beu & Maxwell (1990): Chapter 11; p. 224; pl. 24 k.
Synonymy: Murex zelandicus var. komiticus Suter 1917, p. 37; Chicoreus (?) komiticus; Chicoreus (Siratus) komiticus, Beu & Maxwell 1990, p. 224, pl. 24k.
Classification: Muricidae: Muricinae
Description: Size moderate for subgenus (height 35-50 mm), broadly biconic, spire 0.4 total height. Protoconch conical, of about 4 whorls, last whorl or so with a narrow keel just above suture, otherwise smooth. Teleoconch of 5-6 whorls, convex at first, then becoming bluntly shouldered at third to half whorl height; sutural ramp broad, almost -flat; last whorl contracted to moderately long neck. Varices prominent, rounded, at slightly less than a third of a whorl apart, reaching to top of siphonal canal, bearing a strong, hollow peripheral spine open in front (typically almost horizontal, but directed upwards in holotype). Other axial sculpture on early whorls of rounded costae reaching from suture to suture, not clearly distinguishable from varices at first, then with 1-3 costae between each pair of varices, last 2 whorls usually with a single prominent rounded peripheral tubercle about halfway between varices, some shells with a much weaker additional costa. Spiral sculpture commencing as 4 or 5 moderately strong cords, adult whorls covered with numerous fine cords and threads, rendered finely scabrous by lamellar growth ridges; stronger spirals forming small, open spines where they cross varices on holotype, but scarcely altered on most topotypes. Neck of last whorl with 2 or 3 somewhat stronger cords that form distinct small, open spines at edge of siphonal canal. Aperture ovate; siphonal canal moderately long, almost closed, deflected to left, slightly curved. Inner lip moderately callused with 1 or 2 weak ridges near posterior end and 2 very weak denticles just above siphonal canal. Outer lip projecting slightly in front of terminal varix, slightly concave from suture to periphery, convex below, edge crenulated by internal lirae.
Comparison: The only other New Zealand species of Chicoreus named to date are C. (Triplex) syngenes and C. (Triplex) lawsi, all of which were referred to C. (Triplex) by Houart (1992). C. syngenes was described from Slip Point, Clifden (Clifdenian) where it seems to be very rare, but specimens of Chicoreus from Calamity Point (Altonian) are probably conspecific. These closely resemble C. komiticus in overall appearance, but have shorter peripheral spines and have a single spiral cord on the neck that is much stronger than the two or three present in C. komiticus. Calamity Point shells are up to at least 65 mm in height, much larger than any recorded C. komiticus. C. lawsi (Otaian?, Pakaurangi Point), which was originally described in Murex, differs from C. komiticus and C. syngenes in having varices aligned across succeeding whorls, in having two prominent costae between each pair of varices, and in having coarser spiral sculpture. C. komiticus and C. syngenes superficially resemble some species of Murexsul but differ in having a clear distinction between varices and intervariceal axial sculpture, and in having the outer lip projecting in front of the terminal varix, particularly below the periphery. At least 40 living tropical Indo-West Pacific species of C. (Triplex) were reviewed by Houart (1992).
Distribution: Otaian-Altonian; Pakaurangi Formation, Pakaurangi Point, Kaipara Harbour (type); Paratoetoe Formation, Paratoetoe and Te Pokere, Parengarenga Harbour (uncommon at all localities).
Cite this publication as: "A.G. Beu and J.I. Raine (2009). Revised
descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990). GNS
Science miscellaneous series no. 27."
© GNS Science, 2009
ISBN
978-0-478-19705-1
ISSN 1177-2441
(Included with a PDF facsimile file
copy of New Zealand Geological Survey Paleontological Bulletin 58 in CD version
from: Publications Officer, GNS Science, P.O. Box 30368 Lower Hutt, New
Zealand)